error patterns Archives - Alufinish

Common Error Patterns in Anodising – and How to Prevent Them

Benedikt Wolter — Mon, 19 Jan 2026 11:05:13 +0000

Anodising is one of the most established methods for finishing aluminium surfaces. However, even minor deviations in the process can lead to visible defects and non-saleable surfaces. This article outlines three common error patterns – and how to prevent them reliably. Iridescent Discolouration Due to Contact Faults After anodising, some components show iridescent rainbow colours […]

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Influence of impurities on depth scattering during electrolytical tin colouring of aluminium

Benedikt Wolter — Fri, 21 Feb 2025 10:23:19 +0000

An experiment was conducted to investigate which impurities interfere with depth scattering during electrolytical tin colouring. The aim of the experiment was to determine the influence of individual foreign ions on the homogeneity of the deposited tin layer and the associated optical scattering properties. Experimental procedure For the experiment, EN AW 5005 metal strips were […]

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Microcracks on anodised surfaces

Benedikt Wolter — Fri, 20 Sep 2024 12:53:19 +0000

Anodised aluminium surfaces are characterised by their protective, ceramic-like oxide layer, which can, however, show fine cracks, so-called microcracks, in certain situations. These microcracks often only become visible when the light falls at an angle, whereas they are barely noticeable when viewed directly. They are an indicator of mechanical or thermal stresses on the surface […]

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Cause analysis for drain off marks in anodising

Benedikt Wolter — Thu, 07 Mar 2024 12:24:41 +0000

A common problem in anodising operations: The goods have been chemically pretreated and when the flight bar is transferred to the removal station, you suddenly notice clearly visible drain off marks on the surface that cannot be wiped off. In some cases, colour lightening is even visible on appropriately coloured goods. Goods damaged in this […]

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Iridescent colouring after anodising?

Benedikt Wolter — Mon, 28 Aug 2023 04:00:00 +0000

Occasionally, it arouses astonishment when, after anodising the products, profiles unexpectedly appear that show a differently pronounced iridescent colouring of greenish, reddish and violet tones. This phenomenon does not originate from a pioneering colouring technique, but is rather the result of challenges during anodising. What is the cause? The correct contact is undoubtedly an essential […]

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Extraction of etching mists – How the ventilation of room air can be problematic

Benedikt Wolter — Tue, 28 Feb 2023 19:51:34 +0000

Small, white and unwipeable spots, visible on anodised and electrolytically coloured goods (e.g. C35 - Black), attract the observer's attention immediately and result in unsaleable goods and rework. This makes it even more important to quickly localize and eliminate the cause of the problem. Defect pattern: small, white dots on coloured fabric What had happend? […]

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Screen- and fried egg effect on electrolytically coloured aluminium

Benedikt Wolter — Fri, 04 Nov 2022 19:32:13 +0000

In classical, electrolytic colouring of aluminium surfaces with tin salts, uniform colourings from bronze to black are obtained with correct operation and the right colouring bath settings. However, sometimes you can observe inhomogeneous colouring on the goods carrier, so that a glance at the goods is enough to recognise the non-uniformity. Typical electrolytic colouring process […]

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Small cause – big effect : Mistakes when cleaning in anodising operations

Benedikt Wolter — Mon, 24 Oct 2022 07:14:12 +0000

Even small mistakes while cleaning aluminium surfaces can lead to unsaleable goods in the anodising plant. It is therefore always worthwhile to take a look at the raw material that is about to be pretreated. If there are still residues of adhesive tapes or protective films on the surface, these will most likely be visible […]

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Too much colour due to tin on the surface the problem of over-dyeing

Benedikt Wolter — Tue, 28 Jun 2022 09:17:09 +0000

On anodised, electrolytically black-coloured and hot-sealed aluminum we see deposits - what could that be? After hot sealing, deposits are often visible on anodised and coloured surfaces, which are then quickly classified as so-called " sealing smut". However, if closer inspection reveals that all sealing conditions were in order, the search for the possible defect […]

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The problem with zinc in acidic aluminium etching

Benedikt Wolter — Mon, 07 Mar 2022 15:38:31 +0000

Particularly in the field of job coating, a certain proportion of hot-dip galvanised surfaces has to be treated in addition to a large proportion of aluminium surfaces. If only an acidic etching and degreaser is available for this in the plant, it becomes problematic. If both metals are pretreated in only one etching bath, […]

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